Die assembly

ABSTRACT

An improved die assembly having a split casing and adjustable means bridging said split casing to apply a compressive force to a die body contained within the bore of said casing wherein the inside surface of said casing bore is adapted with a plurality of symmetrically placed, radially extending slots extending a predetermined distance into said casing and terminating in longitudinal bores having a diameter larger than the width of said slots and wherein the center line of said bore is contained within the plane of said radial slot, and said die body is adapted with flats on its otherwise cylindrical outer surface, said flats being aligned longitudinally with the center line of said cylindrical die body such that the surface of said die body when compressively contained within said split casing does not contact the casing in the immediate vicinity of said longitudinal slots so that adverse stresses are not introduced into the casing or die body.

United States Patent [151 3,680,340 51 Aug. 1,1972

Phillips, Jr.

[ DIE ASSEMBLY [72] Inventor: William H. Phillips, Jr.,

Northbergen, NJ.

[73] Assignee: Carnet Company, Pittsburgh, Pa.

[22] Filed: May 1, 1970 [21] Appl. No.: 33,74l

[52] US. Cl. ..72/36, 72/467 [51] Int. Cl. ..B2lc 3/00, B2lb 31/34 [58] Field of Search ..72/467, 36

[56] References Cited UNITED STATES PATENTS 3,109,663 11/1963 Phillips .....72/467 3,243,989 4/1966 Meats ..72/467 3,466,922 9/1969 Phillips ..72/467 2,260,479 10/1941 Picking ..72/36 Primary Examiner-Charles W. Lanham Assistant Examiner-R. M. Rogers AttorneyRichard A. Speer, Vincent G. Gioia and Howard R. Berkenstock, Jr.

[57] ABSTRACT An improved die assembly having a split casing and adjustable means bridging said split casing to apply a compressive force to a die body contained within the bore of said casing wherein the inside surface of said casing bore is adapted with a plurality of symmetrically placed, radially extending slots extending a predetermined distance into said casing and terminating in longitudinal bores having a diameter larger than the width of said slots and wherein the center line of said bore is contained within the plane of said radial slot, and said die body is adapted with flats on its otherwise cylindrical outer surface, said flats being aligned longitudinally with the center line of said cylindrical die body such that the surface of said die body when compressively contained within said split casing does not contact the casing in the immediate vicinity of said longitudinal slots so that adverse stresses are not introduced into the casing or die body.

PATENTEDAUB 1 I972 m n Fe FIG.

FIG. 4.

FIG. 3.

INVENTOR. WILLIAM H. PHILLIPS, JR.

DIE ASSEMBLY BACKGROUND OF THE INVENTION 1 In the past, drawing dies and the like have been formed of refractory metal carbides such as cemented tungsten carbides, sometimes also containing such as titanium, columbium,tantalum, vanadium, and molyd denum carbides and a binder such as cobalt, it being found that such dies give; outstanding performance and have along life as compared to dies formed of other materials. .A variety of different holders have been devised to support and maintainthe dies n an operative position. In most embodiments the dies are assembled in the holders by either the hot shrink method or the cold press method. In assembling the die in the holder by the hot shrink method, the holder is heated to expand same and the die is then inserted into the holder which is then permitted to cool and contract about the die. in the cold press method, the die is usually made having a diameter-slightly in excess of the inner diame- DESCRIPTION OF DRAWINGS FIG. 1 is a front view of the die assembly of my invention. Y

FI 2 is a side elevation, partially sectioned, of the die assembly of my invention.

FIG. 3 is a fragmentary view of a portion of the die assembly of my invention.

ter of the holder and the die isforceably fitted into the holder. Where the die assembly is formed either by the hot shrink method or the cold press method, the assembly is sold as a unit and when sufficient' die wear has occurred, the unit is scrapped unless it may be machined to a larger die opening for use in conjunction with larger diameter workpieces. In the latter case, the unit must be dismounted and the die must be machined while mounted in the holder.

An improved die assembly .of my invention,. v

described in U. S.,Pat. No. 3,109,663, illustrates a die FIG. 4 is a fragmentary section taken along the line lV-lV of FIG. '3.

DESCRIPTION OF THE PREFERRED EMBODIMENT 1 Referring to the drawings in general and particularly to FIGS, l and 2, reference 10 indicates generally the die assembly of my invention. The die assembly 10 includes a support casing 12 having a bore 14 axially therethrough. A generally cylindrical die body 16 is adapted to be compressivelyseated'within bore 14 of casing 12. in the preferred embodiment casing 12 is adapted with a supporting surface 18 being a shoulder assembly in which the die body is readily removable from the assembly. This is accomplished by having a split casing or holder for supporting the cylindricaldie and having locking means operable therewith for applying a compressive force through the casing to rigidly hold the die member in assembled position within the casing. While there are numerous advantages to this die assembly over that previously known in the art, there are also some disadvantages. Among the disadvantages from the split casing design presently known is that a non-uniform compressive loading of the die body occurs asthe locking means is actuated placing .the die body in compressive loading. This uneven loading forces the die body forming surfaces out oftrue shape, e.g., round draw dies become slightly elliptical and shape dies distort across the flat surfaces. Such a distorted die body causes the drawn product to be slightly out of true shape as well as causing adverse wear on certain sections of the die forming surface. The

die assembly of my present invention overcomes these disadvantages in providing a uniformly, compressivelysupported die body within a split casing, thus retaining the features of a readily disassemblable die structure while permitting the use of the more brittle, longer wearing die body materials.

SUMMARY OF THE INVENTION An improved die assembly having a split casing formed by a longitudinally extending slot from the outer wall of said casing through to an axial bore therein, said casing containing acylindrical die body having forming surfaces therein, said split casing adapted with adjustable bridging-means to apply a compressive force to said diebody contained therewithin and said casing adapted with a plurality of symmetrideveloped at a reduced diameter of bore 14.

Die body 16 has an outer cylindrical surface of a predetermined diameter adapted to be closely seated within bore 14 and supported against'the longitudinal forces of drawing by surface 18. Die body 16 may be provided with asuitable'forming surface 20 defining the opening 22 therein providing the passage for a workpiece (not shown) being drawn. r

Support casing 12 may be of a variety of suitable tool steels such as A.I.S.I. 4 340 utilized in the described embodiment which is further hardened to a Rockwell C hardness of from 45 to 47. The die body 16 may be of a variety of materials such as tungsten carbide utilized in the described embodiment for its long life and resistance to wear. The reduced diameter bore 24 in the rearward sectionv of support casing 12 is maintained sufiiciently large so as not to interfere with the workpiece being drawn through die. body 16.

In order to maintain a die assembly 10 capable of a readily removable die body 16, casing 12 is slotted longitudinally to provide slot 26 through the side wall of said support casing 12. Support casing 12 is then provided with bridging means 28 for applying a compresouterperiphery of casing 12. These may be bored into the support casing and adapted to receive a cap screw 34, opening 30 being adapted with threads 36 and opening 32 being adapted with a stepped bore as at 38 As illustrated in FIGS. 2 and 4, support casing 12 may be adapted with a plurality (such as two) bridging mean's to provide a more uniform compressive loading of the die body 16 within the support casing 12. Also illustrated in these figures are the preferred standardization marks 44, 46, and 48 (later described) to provide a standardized repeatabletorqing of the cap screws 34 thereby enabling a standardized repeatable compressive loading of die body 16.

So that locking means 28 cooperating through slot 36 may cause support casing 12 to more uniformly support die body 16 in compression, a pluralitv of longitudinal slots 50 are cut into support casing '12 from bore 14. Contrary to slot 26, slots 50 extend a predetermined distance into the wall of casing 12, but not therethrough. Slots 50 terminate by opening into stress relieving bores 52 aligned longitudinally therewith and extending coextensively with said slots 50 throughout support casing 12 from front to back. The center lines of said bores 52 are preferably located on the center line of slots 50 being radially aligned therewith. To

achieve the maximum uniformity .of compressive loading, slots 50 are located symmetrically around the inside bore 14 of support casing 12, slot 26 being included in the determination of the symmetrical positioning of slots 50. For optimum strength the supporting case wall thickness from outer portion of the stress relief hole 52 to the outer periphery of support casing 12 is maintained as large as possible. Conversely the inner portion of stress relief hole 52 as indicated at 56 should not extend into the casing bore 14 thereby being directly adjacent to die body 16. The inner web 58 thus generated in the preferred embodiment is on the order of l/32nd inch to 1/ 16th inch for practical machining capabilities.

In order to minimize stress concentrations which otherwise would be developed at theopenings of slots distance between the two radii at the periphery of die body 16 any tendency to develop a wedging action in the webs 58 of the slots 50 is minimized thereby lessenin g any tendency of aggravated case fatigue.

In the embodiment disclosed, two stress relief slots 50 in addition to the slot 26 are utilized. It is noted that additional slots may be desirable in embodiments utilizing different case for die body materials or those embodiments of appreciably different dimension than those illustrated.

As previously mentioned, a standardized and repeatable torqing of the locking means 28 is necessary for optimum performance of the die assembly 10. Ap-

plication of standardizing marks 44, 46, and 48 to the 2. Cap screw 34 is tightened and lightlyseated against shoulder 38.

3. Standardization marks 44 and 46 are then located as by being stamped into the casing 12 and top face of the cap screw 34 asindicated in FIG. 2. It is to be noted that these are relatively in the 10:30 oclock position in the illustrated embodiment. However, these might be placed opposite each other relatively around the cap screw 42 to suit the convenience of the user.

4. Cap screw 34 is torqued (clockwise in the illustrated embodiment) with a torque wrench to the proper torqued value.

' 5. Standardization mark 48 is then located as by being stamped in the casing opposite the new rotated location of standardization mark 46.

Thus it may be seen that all a user has to do to properly compressively load a die body 16,'after inserting the die body into the casing, is to turn the cap screw head 42 with torqing means until the'standardization marks are properly aligned. In the event that a cap screw must be replaced,all the replacer must do to restandardize thenew screw is to lightly seat it in the counterbore against shoulder 38 and then stamp the standardization mark on the cap screw head 42 opposite the standardization mark appearing at 44 in the casing 12. The die body may then be compressively loaded to the predetermined desired value by merely torqing the tap screw until the loaded standardization marks (46 and 48) are properly aligned.

Consistent with the invention herein disclosed,

I claim:

1. A die assembly comprising an outer support casing having an axial bore extending therethrough, said casing having a longitudinally extending slot through the side thereof to form a split casing; a removable cylindrical die body disposed to seat within said slotted casing, said die body having an outer periphery in engagement with said casing; adjustment means positioned to bridge the slot of said casing adapted to force the opposite faces of said slot of said casing towards each other to apply acompressive force to said die body to hold said die body in'assembled relation therewith, said casing being provided with a plurality of longitudinal slots positioned around the perimeter and opening into said bore, said cylindrical die body being provided with Iongitudinal portions about the outer periphery thereof out of contact with the casing, said portions being located so as to occur adjacent and in overlying alignment with said slots in said casing to preclude the direct transfer of stresses between the casing and die body in the vicinity of the slots.

2. A die assembly according to claim 1 wherein said slots are radially extending.

3. A die assembly according to claim 2 wherein said slots are equally spaced about the perimeter of said bore.

4. A die assembly according to claim 3 wherein each of said plurality of slots terminates in a stress relieving longitudinally extending bore slightly larger than the associated slot.

5. A die assembly according to claim 4 wherein said longitudinal portions are flats formed in the periphery of the die body.

6. A die assembly according to claim 5 wherein said flats are at least as wide as the corresponding slots.

7. A die assembly according to claim 6 wherein each flat is at least as wide as the distance, at the flat, between two radii projected between the die body center and tangent to the corresponding slot associated stress relieving bore.

8. A die assembly according to claim 1 wherein said slots are equally spaced about the perimeter of said bore.

9. A die assembly according to claim 1 wherein said longitudinal portions are flats, said flats being at least as wide as the corresponding slots.

10. A die assembly according to claim 1 wherein said adjustment means includes a cap screw and said slotted casing is provided with a pair of aligned screw receiving openings extending in opposite directions from the opposite faces of said slot, one of said openings being adapted to engagethe thread on said cap screw'and the other extending to the outer face of said casing and having a supporting shoulder contained therein to engage the cap on said cap screw.

11. A die assembly according to claim 10 wherein said casing and cap screws are adapted with indicator means providing an indication of the compressive loading by said cap screw in said casing, said indicator means providing a notation of the relative position of said cap screw and easing at the initiation of compressive loading and the relative position when said compressive force has reached a predeteremined value.

12. A die assembly according to claim 1 wherein said casing includes means to support said die body against the longitudial forces of forming. 

1. A die assembly comprising an outer support casing having an axial bore extending therethrough, said casing having a longitudinally extending slot through the side thereof to form a split casing; a removable cylindrical die body disposed to seat within said slotted casing, said die body having an outer periphery in engagement with said casing; adjustment means positioned to bridge the slot of said casing adapted to force the opposite faces of said slot of said casing towards each other to apply a compressive force to said die body to hold said die body in assembled relation therewith, said casing being provided with a plurality of longitudinal slots positioned around the perimeter and opening into said bore, said cylindrical die body being provided with longitudinal portions about the outer periphery thereof out of contact with the casing, said portions being located so as to occur adjacent and in overlying alignment with said slots in said casing to preclude the direct transfer of stresses between the casing and die body in the vicinity of the slots.
 2. A die assembly according to claim 1 wherein said slots are radially extending.
 3. A die assembly according to claim 2 wherein said slots are equally spaced about the perimeter of said bore.
 4. A die assembly according to claim 3 wherein each of said plurality of slots terminates in a stress relieving longitudinally extending bore slightly larger than the associated slot.
 5. A die assembly according to claim 4 wherein said longitudinal portions are flats formed in the periphery of the die body.
 6. A die assembly according to claim 5 wherein said flats are at least as wide as the corresponding slots.
 7. A die assembly according to claim 6 wherein each flat is at least as wide as the distance, at the flat, between two radii projected between the die body center and tangent to the corresponding slot associated stress relieving bore.
 8. A die assembly according to claim 1 wherein said slots are equally spaced about the perimeter of said bore.
 9. A die assembly according to claim 1 wherein said longitudinal portions are flats, said flats being at least as wide as the corresponding slots.
 10. A die assembly according to claim 1 wherein said adjustment means includes a cap screw and said slotted casing is provided with a pair of aligned screw receiving openings extending in opposite directions from the opposite faces of said slot, one of said openings being adapted to engage the thread on said cap screw and the other extending to the outer face of said casing and having a supporting shoulder contained therein to engage the cap on said cap screw.
 11. A die assembly according to claim 10 wherein said casing and cap screws are adapted with indicator means providing an indication of the compressive loading by said cap screw in said casing, said indicator means providing a notation of the relative position of said cap screw and casing at the initiation of compressive loading and the relative position when said compressive force has reached a predeteremined value.
 12. A die assembly according to claim 1 wherein said casing includes means to support said die body against the longitudial forces of forming. 